A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain EMBRAER Model EMB-120 series airplanes was published in the Federal Register on September 3, 1998 (63 FR 46932). That action proposed to require replacement of the fairlead support assemblies of the aileron control cable located in the nacelle outboard fittings with new, improved assemblies; and replacement of certain attachment screws with new screws.
Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
Support for the Proposal
One commenter supports the proposed rule.
Request to Withdraw Proposed Rule
Two commenters state that the proposed rule is not warranted and cannot be justified. One commenter, an operator, does not agree that this is a safety of flight issueand states that the proposed AD does not specify the amount of wear found on the cables, or that the cables were in danger of, or close to, failure. In support of withdrawal of the proposed rule, the commenter references two instances, one in 1991 and one in 1997, in which the Brazilian Centro T cnico Aeroespacial (CTA) documented that if a single cable failed during flight, the airplane would be able to land safely. The commenter also states that the EMB-120 Maintenance Review Board (MRB) inspection interval for the aileron cables is sufficient to ensure continued airworthiness in lieu of issuance of the final rule.
Another commenter, the manufacturer, states that inspections of certain airplanes conducted at its facility revealed cables with polished areas, but no indication of wear or rupture was detected. The commenter states also that operators that have not incorporated Revision 2 of the service bulletin have a rigorous inspection interval of every 400 flight hours, per the MRB. For operators that have incorporated Revision 2 of the service bulletin, the cable inspections are to be accomplished at each "5A" check (2,000 flight hours). The commenter states that during the past 10 years it has performed 25 "C" checks with no record of aileron cable replacement due to broken wires.
The FAA does not concur with the commenters requests. The FAA does consider this a safety issue based on the determination that if the aileron cable were to break during a critical portion of the flight, such as during a steep turn or on approach for landing, it would result in reduced controllability of the airplane.
In addition, an investigation of service difficulties conducted by the FAA revealed over 200 reports of aileron cable wear. Although most of these occurred in the early 1990 s, several cases were reported in 1997 and two through mid-1998. This suggests that not all operators are incorporating the service bulletin.
Based on this information, theFAA finds that issuance of the final rule is necessary to ensure an adequate level of safety for the affected fleet.
Request to Revise Inspection Intervals
One commenter states that Parts I, II, and III of EMBRAER Service Bulletin 120-27-0068, Change 02, dated March 20, 1998, include a statement referring to MRB Tasks 27-07 and 27-65 [the correct reference as stated in the service bulletin is Maintenance Planning Guide (MPG) Tasks 27-07 and 27-64] for inspection intervals of the specified areas, both pre- and post-mod. The commenter requests that the inspection interval of the post-mod installation be based on an analysis of inspection findings and an agreement between the operator and its Principal Maintenance Inspector (PMI).
The FAA does not concur with the commenter s request. The FAA finds that, at this time, insufficient data exist to support allowing PMI s to make an assessment of aileron cable wear in order to increase the regular post-mod inspection intervals calledout in the MPG. The FAA may, however, approve a request for an adjustment of the post-mod inspection intervals if data are submitted to substantiate that such an adjustment would provide an equivalent level of safety.
Request to Extend Compliance Time and Add Repetitive Inspections
One commenter requests that the FAA extend the proposed compliance time for the modification from within 400 hours time-in-service after the effective date of this AD, to within 500 hours time-in-service after the effective date of this AD. The commenter also requests that if the FAA proceeds with issuing this AD, inspections of the aileron cables be added; the inspections should be accomplished at intervals not to exceed 500 flight hours until installation of the modification. The commenter indicates that accomplishment of the modification cannot be completed within 400 hours time-in-service due to lack of availability of the kits used for the modification. The commenter states that one-third ofthe compliance time will be used waiting for delivery of the kits.
The FAA partially concurs with the commenter s request. The FAA has determined that allowing repetitive inspections of the aileron cables at intervals not to exceed 500 flight hours "until installation of the modification" is not appropriate in this case because it allows the inspections to continue indefinitely, which does not address the unsafe condition in a timely manner. However, the manufacturer has stated that parts kits are available 90 days after submission of the purchase request. In light of the time required to obtain the parts, the FAA agrees to revise the compliance time for accomplishment of the modification, and to add an option for repetitive inspections in accordance with procedures specified in the airplane maintenance manual. The FAA finds that repetitive inspections of the aileron cable at intervals not to exceed 400 hours time-in-service until accomplishment of the modification, for a timeperiod not to exceed 6 months after the effective date of this AD, will not adversely affect safety, and will allow the modification to be performed at a base during regularly scheduled maintenance where special equipment and trained maintenance personnel will be available if necessary. The Summary section, as well as paragraphs (a) and (b) of this final rule, have been revised accordingly.
Explanation of Change to Proposal
The FAA has added "Note 2" to the final rule to clarify the definition of a general visual inspection.
Conclusion
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.
Cost Impact
The FAA estimates that 227 airplanes of U.S. registry will be affected by this AD.
For airplanes identified in Part I of EMBRAER Service Bulletin 120-27-0068, Change 02, it will take approximately 4 work hours per airplane to accomplish the required replacement of the fairlead support assemblies of the aileron control cable, at an average labor rate of $60 per work hour. Required parts will cost approximately $1,464 per airplane. Based on these figures, the cost impact of this replacement required by this AD on U.S. operators is estimated to be $386,808, or $1,704 per airplane.
For airplanes identified in Part II of EMBRAER Service Bulletin 120-27-0068, Change 02, it will take approximately 1 work hour per airplane to accomplish the required replacement of the fairlead support assemblies of the aileron control cable, at an average labor rate of $60 per work hour. Required parts will cost approximately $1,292 per airplane. Based on these figures, the cost impact of this replacement required by this AD on U.S. operators is estimated to be $306,904, or $1,352 per airplane.
For airplanes identified in Part III of EMBRAER Service Bulletin 120-27-0068, Change 02, it will take approximately 1 work hour per airplane to accomplish the required replacement of the fairlead support assemblies of the aileron control cable, at an average labor rate of $60 per work hour. Required parts will cost approximately $501 per airplane. Based on these figures, the cost impact of this replacement required by this AD on U.S. operators is estimated to be $127,347, or $561 per airplane.
For airplanes identified in Part IV of EMBRAER Service Bulletin 120-27-0068, Change 02, it will take approximately 1 work hour per airplane to accomplish the required replacement of the attachment screws, at an average labor rate of $60 per work hour. Required parts cost will be minimal. Based on these figures, the cost impact of this replacement required by this AD on U.S. operators is estimated to be $13,620, or $60 per airplane.
The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.
Should an operator elect to accomplish the optional repetitive inspections provided by this AD action, it would take approximately 2 work hours per airplane, per inspection cycle, to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspections would be $60 per airplane, per inspection cycle.
Regulatory Impact
The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: